Crude oils or crude petroleums and the middle distillates obtained from crude oils of petroleum origin by distillation, such as gas oil, diesel motor fuel or domestic fuel oil, contain, depending on the origin of these crude oils, different quantities of n-alkanes or n-paraffins which at a low temperature, typically below 0° C., crystallize out as lamellar crystals which have a tendency to agglomerate. There is then a deterioration in the flow characteristics of the oils and distillates. Difficulties occur during transport, and/or storage of the oil or fuel. The wax crystals have a tendency to clog and block pipes, fuel lines, pumps and filters, for example in vehicle fuel systems.
In winter or in conditions of use of the oil, petroleum or the distillate at a temperature close to below 0° C., the crystallization phenomena can lead to deposits on the fuel line walls, even to a complete blockage. These problems are well known in the field of motor fuels and liquid hydrocarbon fuels where numerous additives or mixtures of additives have been proposed and are marketed for reducing the size of the wax crystals and/or changing their shape and/or preventing their formation. The smallest possible crystal size is preferred as it minimizes the risks of blockage or clogging the filter.
The usual agents for improving the flow of crude oils and middle distillates are co- and ter-polymers of ethylene and vinyl and/or acrylic ester(s) alone or in a mixture with low molecular weight oil-soluble compounds or polymers which contain one or more ester, amide, imide, ammonium groups substituted by at least one alkyl chain. Apart from improving the flow of the oil and the distillate, another purpose of the additives for improving the flow is to ensure the dispersion of the wax crystals so as to delay or prevent the settling of the wax crystals and therefore the formation of a layer rich in waxes at the bottom of receptacles, vessels or storage tanks. These additives for dispersing waxes are called WASA (acronym for the term wax anti-settling additive).
The alkylphenol-aldehyde resins originating from the condensation of alkylphenol and aldehyde have been known for a long time as agents for improving the flow of mineral oils: see for example EP 311 452 which describes condensation products of at least 80% mol of dialkylphenols and aldehydes having 1 to 30 carbon atoms; EP0857776 which describes the use of alkylphenol-aldehyde resins in which the alkyl groups of the alkylphenol have 4 to 12 carbon atoms and the aldehyde has 1 to 4 carbon atoms and containing no more than 10% mol of alkylphenols having more than one alkyl group, in combination with ethylene/vinyl ester co- or ter-polymers for improving the fluidity of mineral oils; EP1584673 which describes alkylphenol-aldehyde resins of Mn between 1000 and 3000 originating from the condensation of a C1-C4 aldehyde and a mixture of alkylphenols with a majority of monoalkylphenol, the alkyl group having 1 to 20 carbon atoms intended to improve the low temperature flow properties of motor fuel compositions. Modified alkylphenol-aldehyde resins have also been proposed as additives for improving the low temperature flow of mineral oils: EP1767610 describes alkylphenol resins the condensation reaction of which with the aldehydes is carried out in the presence of fatty acids having 2 to 50 carbon atoms, or their derivatives, such as esters. Recently, the applicant company in patent applications with filing numbers FR2010/61193 and PCT/IB2011/055863 has proposed novel modified alkylphenol-aldehyde resins which can be used for improving the low temperature stability of motor fuels and liquid hydrocarbon fuels and more particularly by limiting the settling of waxes contained in the motor fuels and fuels at low temperature.
These modified alkylphenol-aldehyde resins can be obtained by a Mannich reaction of an alkylphenol-aldehyde condensation resin                with at least one aldehyde and/or one ketone having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms;        and at least one hydrocarbon compound having at least one alkylmonoamine or alkylpolyamine group (i.e. having several amine groups) having between 4 and 30 carbon atoms,        the alkylphenol-aldehyde condensation resin can itself be obtained by condensation        of at least one alkylphenol substituted by at least one linear or branched alkyl group having 1 to 30 carbon atoms, preferably a monoalkylphenol,        with at least one aldehyde and/or one ketone having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms.        
In continuing its work, the applicant company has discovered that a specific combination of such modified alkylphenol-aldehyde resins with at least one specific filterability additive makes it possible to further improve the low temperature properties, in particular the low temperature behaviour of motor fuels and liquid hydrocarbon fuels. The applicant company has, in particular, discovered an additive composition making it possible to reduce the cold filter-plugging point while maintaining the dispersant and/or anti-settling effect of the modified alkylphenol-aldehyde resins described in patent applications FR2010/61193 and PCT/162011/055863.
The purpose of the present invention consists of proposing additive compositions for improving the low temperature behaviour of the motor fuels and liquid hydrocarbon fuels, in particular, the boiling temperature range of which is comprised between 100 and 500° C., even above 500° C. Another purpose of the present invention consists of proposing improved additive compositions for reducing the cold filter-plugging point while limiting the settling of waxes. The present invention also relates to an additive composition capable of being added to motor fuels and liquid hydrocarbon fuels comprising at least one additional filterability additive for reducing the cold filter-plugging point without affecting the effectiveness of the modified alkylphenol-aldehyde resin on the dispersion and/or the settling of waxes.
The present invention relates, in particular, to a composition of motor fuels and liquid hydrocarbon fuels having a low cold filter-plugging point (according to the standard NF EN 116), advantageously less than or equal to −25° C., preferably less than or equal to −27° C., more preferentially less than or equal to −28° C. and even more preferentially less than or equal to −29° C. The present invention also relates to a composition of motor fuels and liquid hydrocarbon fuels having a settling volume according to the ARAL test of less than 10 mL and/or a delta CFPP before/after settling (according to the standard NF EN 116) less than or equal to 1° C. and/or a delta CP before/after settling (according to the standard NF EN 23015) less than or equal to 1° C.
According to the invention this purpose is achieved by an additive composition comprising:                at least one modified alkylphenol-aldehyde resin capable of being obtained by Mannich reaction of an alkylphenol-aldehyde condensation resin                    with at least one aldehyde and/or one ketone having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms;            and at least one hydrocarbon compound having at least one alkylmonoamine or alkylpolyamine group (alkylamine) having between 4 and 30 carbon atoms,                         the alkylphenol-aldehyde condensation resin itself being able to be obtained by condensation                    of at least one alkylphenol substituted by at least one linear or branched alkyl group having 1 to 30 carbon atoms, preferably a monoalkylphenol,            with at least one aldehyde and/or one ketone having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, and                        at least one filterability additive chosen from:                    the terpolymers of C4 to C22 alkyl (meth)acrylate, C20 to C24 alpha-olefin and maleimide N-substituted by a hydrocarbon chain having between 4 and 30 carbon atoms,            the homopolymers of C1 to C40 alkyl (meth)acrylate, preferably the C8 to C24 alkyl polyacrylates,            the ammonium salts of mono- or poly-carboxylic acid comprising at least one linear or branched, saturated or unsaturated hydrocarbon chain and having between 4 and 30 carbon atoms.                        
According to a preferred embodiment, the filterability additive is chosen from:                the homopolymers of C1 to C40 alkyl (meth)acrylate, preferably the C8 to C24 alkyl polyacrylates,        the ammonium salts of mono- or poly-carboxylic acid comprising at least one linear or branched, saturated or unsaturated hydrocarbon chain and having between 4 and 30 carbon atoms.        
The subject of the invention also relates to an additive composition comprising:                at least the modified alkylphenol-aldehyde resin,        at least one first filterability additive chosen from the homopolymers of C1 to C40 alkyl (meth)acrylate, preferably the C8 to C24 alkyl polyacrylates and,        at least one second filterability additive chosen from:                    the terpolymers of C4 to C22 alkyl (meth)acrylate, C20 to C24 alpha-olefin and maleimide N-substituted by a hydrocarbon chain having between 4 and 30 carbon atoms,            the ammonium salts of mono- or poly-carboxylic acid comprising at least one linear or branched, saturated or unsaturated hydrocarbon chain and having between 4 and 30 carbon atoms.                        
According to a development, the ammonium salts are ammonium salts of mono- or poly-carboxylic acid comprising at least one linear or branched, saturated or unsaturated hydrocarbon chain and having between 4 and 30 carbon atoms and of fatty amine and/or of ethoxylated fatty amine. According to another development, the modified alkylphenol-aldehyde resin is capable of being obtained from at least one alkylphenol substituted in para position, preferably from p-nonylphenol.
In particular, the modified alkylphenol-aldehyde resin is capable of being obtained from at least one aldehyde and/or one ketone chosen from formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2-ethyl hexanal, benzaldehyde, acetone, and preferably from at least formaldehyde. According to a variant, the modified alkylphenol-aldehyde resin is capable of being obtained from at least one alkylamine having at least one primary amine group, and advantageously at least one compound of which all their amine groups are primary amines. According to another variant, the modified alkylphenol-aldehyde resin is capable of being obtained from p-nonylphenol, formaldehyde and at least one hydrocarbon compound having at least one alkylmonoamine or alkylpolyamine group.
In particular, the modified alkylphenol-aldehyde resin is capable of being obtained from at least one alkylamine with a fatty chain or from a mixture of alkylamines with a fatty chain and preferably from alkylamine(s) having a number of carbon atoms between 12 and 24, preferably between 12 and 22. According to a variant, the modified alkylphenol-aldehyde resin has a viscosity at 50° C. measured using a dynamic rheometer at a shear rate of 100 s−1 on a solution of said resin diluted with 30% by mass of an aromatic solvent comprised between 1,000 and 10,000 mPa·s, preferably 1,500 and 6,000 mPa·s and advantageously between 2,500 and 5,000 mPa·s.
Another subject of the invention relates to an additive composition comprising in addition at least one additional filterability additive chosen from the copolymers and terpolymers of ethylene and of vinyl ester and/or of acrylic ester (EVA and/or EVP). According to a development, the additional filterability additive is chosen from the copolymers of ethylene and vinyl ester (EVA). Another subject of the invention also relates to the use of an additive composition according to the invention, in a motor fuel or a liquid hydrocarbon fuel comprising, preferably, at least one filterability additive chosen from the copolymers and terpolymers of ethylene and vinyl ester and/or acrylic ester, for improving the low temperature properties, in particular for reducing the cold filter-plugging point (CFPP) measured according to the standard NF EN 116, without affecting the effectiveness of the modified alkylphenol-aldehyde resin on the dispersion and/or the settling of waxes. Another subject of the invention relates to the use of a composition according to the invention, in motor fuels and liquid hydrocarbon fuels, for improving the low temperature properties of motor fuels and liquid hydrocarbon fuels.
In particular, the use of such a composition, for reducing both the cold filter-plugging point and the dispersion of waxes and/or for limiting the settling of waxes in motor fuels and liquid hydrocarbon fuels. According to a variant, the motor fuels and/or fuels have a boiling range from 120 to 500° C., preferably 140 to 400° C. and, advantageously, are chosen from jet fuels, gas oils, diesel fuels, domestic fuel oil and heavy fuel oil.
Finally, the present invention relates to a composition of motor fuels or liquid hydrocarbon fuels the boiling temperature range of which is mainly comprised between 100 and 500° C. comprising:                a major proportion of hydrocarbon compounds and/or of vegetable and/or animal oils and/or their oil esters and/or of biodiesels of animal and/or vegetable origin, and        a minor proportion, preferably comprised between 5 and 5,000 ppm by mass, of at least one composition according to the invention.        